Why It’s Tough for Fish in the Susquehanna These Days

If you’re a smallmouth bass in the Susquehanna River in Pennsylvania, chances are you’re pretty lonely these days. After a population crash in 2005 where fewer young bass were surviving into adulthood, fisherman also noticed that smallmouth bass are being plagued with tumors and lesions. To add insult to injury, there was also an increase in male fish carrying eggs. In short, it’s been a tough ride as a smallmouth bass in the Susquehanna River. Plus, these problems have put a dent in Pennsylvania’s $3.4 billion recreational fishing industry.

Smallmouth bass. Photo by Spencer Neuharth, U.S. Fish and Wildlife Service

The instersex issue is not limited to the Susquehanna River. In fact, it’s a problem that’s been plaguing fish in National Wildlife Refuges up and down the east coast. A study by the U.S. Fish and Wildlife Service of 19 National Wildlife Refuges on the east coast revealed that 85% of all the smallmouth bass they examined showed signs of female reproductive parts.

Also, it’s not just the poor smallmouth bass that’s been suffering with the intersex problem. Over the past decade, feminized male fish have been discovered in 37 species in lakes and rivers throughout North America, Europe, and other parts of the world.

Fish tumor. Photo by Pennsylvania Fish and Boat Commission

What’s been causing these fish tumors and lesions and intersex fish? Researchers have been pouring over water quality data for years, trying to find an answer. We think we’ve finally identified the culprits. In December 2015, the Pennsylvania Department of Environmental Protection (DEP) and the Pennsylvania Fish and Boat Commission (PFBC), along with nearly 50 participants and 6 partner agencies released findings that narrowed the cause down to two things: endocrine disruptors/herbicides and pathogens/parasites.

Where are these problems coming from and what can we do about it? Endocrine disruptors and herbicides can come from many sources including industry, agricultural, municipal sewage treatment plants, as well as residential and commercial landscaping. Endocrine disruptors, which mimic or block hormones and stop the body from functioning normally, are found in synthetic plastics, detergents, pharmaceuticals, pesticides, and industrial chemicals. They can end up in our streams and rivers through our sewage system, which doesn’t treat waste water for these types of pollution. The herbicides farmers and residents put on their crops and lawns to kill nuisance bugs don’t just stay there; rain washes them off into local streams and rivers, where they harm fish and other wildlife.

What can you do to help the smallmouth bass recover?

Avoid using pesticides in your home or yard, or on your pet — use baits or traps instead, keep in your home especially clean to prevent ant or roach infestations.